Grylls needed to be airlifted from a mountainside in the Canadian Rockies with a badly damaged leg after a camera on a sled slammed into him, the most heart-stopping moment in seven new episodes of the series that starts on Wednesday at 9 p.m. EDT.

The enthusiastic survivalist had glissaded down a mountain, zipping down the snow on his backside, and stopped himself suddenly by using an ice pick. The camera following him didn't stop, missing Grylls' head and shoulder by inches before hitting him in the leg. It didn't break a bone, but came awfully close.

Then the tears came. It had been a stressful stretch of filming, and the emotion of it all came rushing out. The tough guy is only so tough.

"It was a wake-up call," Grylls said. "You've just got to get it right every time. You live with danger a lot and you can get blase, and just can't do that."

Grylls should know. His career in the British military ended when he broke his back after a parachute failed following a jump from a helicopter. He moved into the lucrative world of TV adventure, where his never-flagging enthusiasm, willingness to eat virtually anything (sheep's eyeball, anyone?) and inventive use of common items such as shoelaces to survive uncommon danger made him a compelling draw. (He stuck shoelaces into the crevice of a rocky cliff to collect water when his bottle was nearly empty.)

Discovery viewers relate to Grylls and enjoy the opportunity to live vicariously through his adventures, said Stephen Reverand, Discovery's senior vice president for development and production. Beyond the upcoming episodes, Discovery has committed to filming at least 10 more missions starting in September, he said.

The show has recovered from an embarrassment four years ago when it was revealed Grylls had spent time indoors on a mission where the impression was given that he was outdoor in forbidding conditions the whole time.

"What it underscored for us was the continued importance of authenticity and full disclosure," Reverand said.

Never one to make an easy entrance, Grylls descends into Death Valley for one episode this season following a high-altitude skydive. He jumps from 33,000 feet in temperatures more than 25 degrees below zero, at a point he can see the curvature of the Earth. He free-falls for three minutes before his parachute opens and lands in an astronaut-like suit in temperatures over 125 degrees.

Shortly after the jump, however, his breath intake tube freezes over. He's up so high that taking off his mask is inadvisable: The oxygen is so thin that he'd quickly lose consciousness.

Grylls held his breath for about 30 seconds, hoping fruitlessly the ice would melt, before ripping off the mask. With the lower altitude and slightly warmer temperatures, there was more oxygen. He was unhurt.

He's filmed 65 episodes so far. This season, Discovery airs a behind-the-scenes episode that explains how the series is filmed, and another piece in which Grylls takes two of the show's fans on an adventure. There's no celebrity trek like last year's with Will Ferrell in Sweden.